It’s that one thing that ruins the moment and kills your suspension of disbelief. It’s called deus ex machina (god from the machine), If that word makes you think of the Deus Ex video game series and not the ultimately cheese plot device writers use when they write themselves into corners, then you have some reading to do.
In short, deus ex machina is when the plot reaches a seemingly unsolvable or impossible situation which is thereby resolved by the intervention of a new character, ability, etc. It can be used comically but unfortunately it’s also been used by serious writers (even famous ones) in an effort to shock the audience. Yet they never explain why or how it happened.
From the fantasy novels I’ve read, most authors are pretty good about avoiding this. However, there is that 10% that I’ve read that made me want to chuck the book out of the window. In the early ages of the fantasy genre, this plot device was more readily used because the genre was young and underdeveloped. In the fantasy writing world of today, I often wonder why authors have continued to use this plot device and somehow get away with it. They throw the character into an impossible situation and then get them out of it because – jazz hands – they just did!
When you first start your story, be sure to have all of the scenes down on paper. You should have a clear and detailed outline of every scene in your novel/short story/etc before you actually sit down and write. If you have a solid plan, then it is much easier to avoid getting stuck in a corner and making the mistake of trying to write your way out. Suspension of disbelief is important when writing in the fantasy genre. If you craft characters that readers can’t relate to or concoct a world that’s too fantastical for readers to wrap their head around, you’re not going to keep their attention.
How do we avoid all of this? Foreshadowing can be a great tool to introduce a plot device to your reader before it happens. Just be sure that when you foreshadow something, it is relevant not long after it’s been mentioned, otherwise the reader might forget all about it. That’s where pacing is important.
Let’s talk about an example of where foreshadowing, if removed, makes the story seem folly. In the The Lord of the Rings: The Two Towers, Gandalf rides off to find help before the Battle of Helm’s Deep. You know that Gandalf is doing this because he tells Aragorn that at dawn, look to the east. So before the battle even begins, you know the characters don’t have to win the battle, but survive the onslaught of the antagonist force’s daunting numbers until daybreak. If, however, you removed that whole bit with Gandalf explaining to Aragorn that he was going to go find help and instead he just randomly shows up with a bunch of cavalry at his back, it would be considered deus ex machina.
Some might argue that Gandalf’s rescue is still deus ex machina due to the impossibility of the situation at Helm’s Deep, but I hope you get what I am trying to convey. Jazz hands.